In the recent automotive industry, there have been performed research and development for the improvement of fuel efficiency according to the increase of the global interest in the environment and energy. Also, in order to satisfy the various demands of users, there has been steadily performed research and development towards lightweight, compact and multi-functional automobiles as well as evaporators having increased thermal performance in a compact structure.
The evaporator is a component of an air conditioner system, in which the air introduced by an air blower is cooled by heat exchange while a liquid heat exchange medium is converted into a gas phase such that the cooled air is supplied to the inside of a vehicle.
FIG. 1 shows a prior art evaporator, and FIG. 2 to FIG. 4 respectively show the schematic flow refrigerant flow in the evaporator of FIG. 1, temperature interpretation result for the second line of the evaporator, and the refrigerant speed interpretation result thereof.
The prior art evaporator 80, as shown in FIG. 1 and FIG. 2, includes: a first header tank 10 and a second header tank 20, each of which inside is divided into a first line and a second line by a partition wall 70 and which are provided in parallel to each other at a predetermined distance from each other; an inlet pipe 30 and an outlet pipe 40, which are formed at one side of the first header tank 10; a baffle 50 provided to the inside of the first header tank 10 or the second header tank 20 so as to control the flow of refrigerant; and a core part 60 including a plurality of tubes 61, of which both ends are fixed to the first header tank 10 and the second header tank 20 and a plurality of fins 62 interposed between the tubes 61.
Herein, the refrigerant, introduced through the inlet pipe 30 into the first line, sequentially passes through: a first area A1 (from the top to the bottom) extending in the lengthwise direction in the first header tank 10 to the second header tank 20 through the tubes 61; a second area A2 (from the bottom to the top) extending to the first header tank 10 through other tubes 61; a third area A3 (from the top to the bottom) extending to the second header tank 20 again through still other tubes 61; a fourth area A4 (from the bottom to the top) extending to the second line through a communication part (not shown, a predetermined area of the partition wall in the second header tank 20 is formed to be hollow) and then extending to the first header tank 10; and a fifth area A5 (from the top to the bottom) extending to the second header tank 20 again through still other tubes 61; and a sixth area A6 (from the bottom to the top) extending to the first header tank 10 again through the other tubes 61 and, after that, is discharged through the outlet pipe 40.
However, as shown in FIG. 3 and FIG. 4, according to the prior art evaporator 80, the refrigerant is concentrated on the areas adjacent to the inlet pipe 30 and the outlet pipe. In particular, the second line provided with the outlet pipe 40 is likely to have an area, in which the refrigerant flow is weak by the concentration of the refrigerant due to the inertia thereof, and thus temperature becomes increased in this area. FIG. 4 shows sections of a predetermined speed or higher, indicated by oblique lines. More specifically, the evaporator 80 described above has areas of a relatively high temperature in the range of 8 to 10° C., wherein the temperature difference between the fourth area and the sixth area is the largest, which is 8° C. to the maximum. In addition, there are wide sections, of which a speed is below the predetermined speed. As described above, if the refrigerant distribution in the evaporator 80 is non-uniform, the thermal performance of the evaporator 80 becomes decreased and thus a temperature difference is generated in the air discharged to the left and right sides in the vehicle room, thereby decreasing the temperature comfort of users. The problems as described above become more serious when the amount of the refrigerant in the evaporator becomes decreased and thus the flow rate thereof becomes low.
Korean Reg. Patent No. 10-1130038 (Title of the Invention: Vehicle HVAC system using a 6-pass tube-fin type evaporator using refrigerant containing HFO 1234yf, Published: 20 Dec. 2010)